Chapter 4, Metalinguistic Abstraction

Exercise 4.46

Because the parser reads from left to right it won’t work if evaluator evaluates from right to left.

The whole grammar rules will go wrong for eg: simple noun is article followed by noun when read from left to right. But reading from right to left won’t work.

What we could have done if evaluator is right to left?

Well, I think simply reversing the input would have made it work then.